1. Get Ready to Bake: Preheat your oven to 350°F (175°C). Lightly grease two 9-inch round cake pans and line their bottoms with parchment paper circles. This simple trick ensures your cakes release perfectly!
2. Cream the Goodness: In a large mixing bowl, beat the softened butter and granulated sugar together for 2-3 minutes until the mixture looks wonderfully light and fluffy. Now, beat in the eggs one at a time, followed by the vanilla extract, until everything is smoothly combined.
3. Mix Wet & Dry Smartly: In a separate bowl, quickly whisk together the flour, baking powder, and salt. Gently add about half of this dry mixture to your wet butter-sugar mixture, mixing on low speed just until it starts to come together. Then, add half of the sour cream and milk, mixing briefly until incorporated. Repeat with the remaining dry ingredients, then the rest of the sour cream and milk. Remember to scrape down the sides of the bowl to ensure an even batter, but be careful not to overmix!
4. Bake to Golden Perfection: Divide your perfectly mixed cake batter evenly between the two prepared pans. Bake for 30 to 35 minutes. You'll know they're ready when a toothpick inserted into the center of a cake layer comes out clean. Don't overbake, as this helps keep your cake deliciously moist.
5. Cool Your Layers: Let the baked cake layers cool in their pans for about 10 minutes. After that, carefully invert them onto a wire rack to cool completely. If your cake tops aren't perfectly flat, you can gently level them with a serrated knife once fully cooled.
6. Start the Caramel Magic: In a large saucepan or Dutch oven, combine the cubed butter, granulated sugar, and evaporated milk. Cook this mixture over medium heat, stirring until the butter has fully melted and everything is well combined.
7. Slow Caramelization: Reduce the heat to medium-low. This is where the magic happens! Continue to cook the mixture for about 1.5 to 2 hours, stirring occasionally to prevent burning. Use a candy thermometer clipped to the side of the pan to reach 240°F (the soft-ball stage). This patient cooking process builds that incredible, deep caramel flavor and beautiful color.
8. Perfect the Frosting: Once the thermometer hits 240°F, remove the pan from the heat and stir in the vanilla extract. Allow the caramel frosting to cool for about 20 to 25 minutes – it will naturally thicken. For an extra smooth and spreadable consistency, you can beat the cooled icing vigorously with a sturdy wooden spoon or in a stand mixer (with a paddle attachment) for another 20-25 minutes until it's glossy and thick. If it gets too thick, a tiny splash of milk will help loosen it up.
9. Assemble Your Masterpiece: Place one cooled cake layer on your serving plate or cake stand. Spoon a generous amount of your homemade caramel frosting over the top and spread it out evenly. Gently place the second cake layer on top. Pour the remaining luscious frosting over the entire cake, letting it beautifully cascade down the sides. Use a knife to spread it around the sides with rustic, elegant swooshes.
10. Chill and Enjoy: For the best presentation and to help the frosting set, refrigerate your finished cake for 30 to 60 minutes. Then, slice into this delightful homemade treat and savor every moment!